Plasma generation device including matching device, and impedance matching method

Abstract

The present disclosure relates to a plasma generator having a matching apparatus for matching impedances, and an impedance matching method. The plasma generator includes an RF power supply unit, a load device part including a standard load having a predetermined impedance and an antenna-plasma device configured to generate plasma, and a matching unit configured to connect the RF power supply unit to any one of the antenna-plasma device or the standard load, and match impedances of the RF power supply unit and the antenna-plasma device when the RF power supply unit is connected to the antenna-plasma device, wherein the matching unit is configured to detect a parasitic impedance according to parasitic components inside a circuit by connecting the standard load and the RF power supply unit, connect the antenna-plasma device, when the parasitic impedances are detected, calculate reactance required for the impedance matching, and change capacitance.

The invention claimed is: 
     
       1. A plasma generator, comprising:
 a Radio Frequency (RF) power supply unit configured to supply RF power for plasma generation; 
 a load device part including a standard load having a predetermined impedance and an antenna-plasma device configured to generate plasma according to the RF power; and 
 a matching unit configured to connect the RF power supply unit to any one of the antenna-plasma device or the standard load, and match impedances of the RF power supply unit and the antenna-plasma device when the RF power supply unit is connected to the antenna-plasma device, 
 wherein the matching unit is configured to:
 detect a parasitic impedance according to parasitic components inside a circuit by connecting the standard load and the RF power supply unit before connecting the antenna-plasma device and the RF power supply unit; 
 connect the antenna-plasma device, instead of the standard load and detect a reflection coefficient, when the parasitic impedances are detected; 
 calculate reactance required for the impedance matching by calculating the antenna-plasma impedance based on the detected parasitic impedance and the detected reflection coefficient; 
 change capacitance of capacitors provided therein according to the calculated reactance to match the antenna-plasma device with the RF power supply; 
 perform rematching by changing the capacitance of the matching unit capacitors based on a difference in impedance, when the difference between an impedance detected while the antenna-plasma device is connected to the RF power supply and a preset reference matching impedance is out of a preset range; and 
 when the number of times the rematching is performed exceeds a preset number of times, determine that a calibration process for detecting the parasitic impedance is necessary and perform the calibration process. 
 
 
     
     
       2. The plasma generator of  claim 1 ,
 wherein the matching unit is configured to perform the impedance matching according to whether a calibration process for detecting the parasitic impedance is necessary when the RF power supply unit is connected to the antenna-plasma device, or detect the parasitic impedance through the calibration process by connecting the RF power supply unit to the standard load, instead of the antenna-plasma device, and 
 wherein whether the calibration process is necessary is determined based on whether there is a previously-detected parasitic impedance, whether a system has been initialized, or whether there is a user selection for performing the calibration process. 
 
     
     
       3. The plasma generator of  claim 1 , wherein the matching unit detects a reflection coefficient for RF power supplied to the standard load when the standard load is connected to the RF power supply unit, and detects the parasitic impedance based on the detected reflection coefficient and an impedance of the standard load. 
     
     
       4. The plasma generator of  claim 3 , wherein the matching unit varies the capacitance of the capacitors to detect different reflection coefficients at least two times for the respective capacitance variations, and calculates a reflection coefficient when the standard load is connected to the RF power supply unit based on an average of the detected reflection coefficients. 
     
     
       5. A matching method of a matching unit for matching an impedance of a Radio Frequency (RF) power supply unit and an impedance of an antenna-plasma device generating plasma when the antenna-plasma device is connected to the RF power supply unit, the method comprising:
 connecting the RF power supply unit to a standard load having a preset impedance, instead of the antenna-plasma device, to detect a parasitic impedance according to parasitic components inside a circuit; 
 reconnecting the RF power supply unit to the antenna-plasma device when the parasitic impedance is detected; 
 measuring a reflection coefficient according to RF power supplied to the antenna-plasma device when the antenna-plasma device is connected; 
 calculating a reactance value required for the impedance matching based on the measured reflection coefficient and the detected parasitic impedance; and 
 performing the impedance matching by changing capacitance of variable capacitors provided in the matching unit, so as to generate reactance according to the calculated reactance value, 
 wherein the performing of the impedance matching comprises:
 detecting a difference between an impedance measured when the RF power supply unit is connected to the antenna-plasma device and a preset reference matching impedance; and 
 performing re-matching by changing the capacitance of the variable capacitors based on the detected difference in impedance when the detected difference in impedance is out of a preset range, and 
 
 wherein the performing of the re-matching comprises re-detecting a parasitic impedance by performing the detection of the parasitic impedance again when a number of times of performing the re-matching exceeds a preset number of times. 
 
     
     
       6. The method of  claim 5 , further comprising, prior to detecting the parasitic impedance, determining whether it is necessary to detect the parasitic impedance, wherein the detecting of the parasitic impedance and the reconnecting of the antenna-plasma device are performed according to a result of the determination as to whether it is necessary to detect the parasitic impedance. 
     
     
       7. The method of  claim 6 , wherein the determination as to whether it is necessary to detect the parasitic impedance is made according to whether there is a previously-detected parasitic impedance, whether a system has been initialized, or whether there is a user selection for performing a calibration process. 
     
     
       8. The method of  claim 5 , wherein the performing of the re-matching comprises:
 re-performing the connection to the antenna-plasma device and the measurement of the reflection coefficient, when the parasitic impedance is re-detected; 
 recalculating a reactance value required for the impedance matching based on the re-detected parasitic impedance; and 
 re-performing the impedance matching by changing the capacitance of the variable capacitors provided in the matching unit, so as to generate reactance according to the recalculated reactance value. 
 
     
     
       9. The method of  claim 5 , wherein the detecting of the parasitic impedance comprises: detecting a reflection coefficient for the standard load corresponding to RF power supplied when the standard load is connected to the RF power supply unit; and detecting the parasitic impedance based on the detected reflection coefficient for the standard load and an impedance of the standard load. 
     
     
       10. The method of  claim 9 , wherein the detecting of the reflection coefficient for the standard load comprises: changing capacitance of the variable capacitors and detecting different reflection coefficients for the respective variations a plurality of times; and calculating the reflection coefficient for the standard load based on an average of the detected reflection coefficients.